Originally published at: https://boingboing.net/2018/03/15/cheap-ebay-solder-vs-the-good.html
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Was under the impression that you should never touch the iron tip to your solder… heat the parts and flow the solder when the parts are hot enough to flow it. Otherwise you get cold joints / unuly beads of solder.
Am I way off base here? Do people really solder like ths video?
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I was thinking the same thing. I don’t do much work on PCBs but some of those from the second set seemed like classic ‘cold joints’.
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It looks like good technique to me. You always touch the tip of the iron briefly to get things started. The melted solder then transfers heat better to the working pad. Even at 375 the iron wasn’t hot enough for the cheap solder to make a really good joint. I have no idea what the make-up was, but it wasn’t 60/40. The cheap stuff needed temperatures too high to safely solder the pads he was testing on.
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Doesn’t matter so much. For through-hole work, I use 63/37 eutectic and always get a shiny finish irrespective of technique.
Manual surface mount soldering is a more challenging chore. The lead-free formulations need more surface preparation and a suitable flux for shiny results.
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Wow! That was some nasty stuff! I’m surprised he didn’t lift a trace.
His technique was correct for what he was doing. He was adding solder to a bare pad, Typically you heat the part and add the solder to that. But you have to modify that when adding solder to a bare pad, it helps to hit the iron with it to avoid overheating and lifting the pad.
I’m spoiled, I have a few rolls of Kester in various diameters. I’m not likely to use them all before I die.
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FYI, Kester publishes a short informative table on their solder alloys.
Kester Alloy Temperature Chart
For too much information, see Indium Corp.
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TIL: if you want lead-free devices, you’d better be ready to bring on the heat.
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It had actually never occurred to me that there would be much difference between brands of solder. This explains a lot.
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I wonder if there’s a video comparing knockoff soldering irons/stations to main brands for similar results? I’ve been using a Hakko knock off for a few months and it’s done okay but I always wonder if half my problems is due to the rated temperature being majorly off. I’ve had even leaded solders not flow as nicely as I would like with my particular soldering iron. It can get frustrating when I’m trying to build even with through hole components.
There are some reasonably priced thermocouple-based temperature measuring stations designed to check soldering iron temperatures. I’ve been using one of these Xytronic testers for years. May no longer be available from Xytronic but I’ve seen them around with different labels. Hakko also has one that’s currently in production and available the usual online sources.
These use a Type K thermocouple junction that you heat with the iron; work pretty well. The Hakko can be purchased with a traceable calibration certificate.
In practice I’ve found mine to be a little fussy but it’s another data point and better than just a swag.
And, of course, you can go with some fancy temperature testing stations that are an order of magnitude more expensive. Soldering equipment seems to be like that. A cheap $10 iron, or a pretty good $100 iron, or a hope-the-company-buys-it $1000 Pace station.
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I HATE soldering with or on something assembled using ROHS solder. I understand the need for it, but it still sucks.
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How do you even do it at those temps without popping traces all over the place? (I am not an expert at PCB stuff nor a particularly adept solderer, so…)
Even though it clearly wasn’t 60/40, the ‘cheap’ stuff did wet the pin better than the ‘good’ stuff did. It might have performed better at a little higher temp–and it didn’t flow down the through hole well either. A little more temp might have fixed that.
What this tells me is that the ‘cheap’ stuff really was designed for higher temperature soldering–because it has the rigth temperature of flux with it–and was later re-marked by someone and sold as something it wasn’t. It also tells me that the ‘good’ solder either had the wrong flux or was being used incorrectly–wrong temp.
I routinely solder at 350C and have never had a lifted a trace. The only times I’ve had problems with that are when I had to remove a large part–and I don’t have a dedicated removal setup–and I needed to crank the temp up to 450C to get enough heat transfer. Note that I’m not using the correct technique to remove those parts, so problems like lifted traces are expected.
You’re very unlikely to get a lifted trace at these temps without some kind of mechanical abuse as well. So, if you’re just adding solder to a set joint, these temps shouldn’t damage the board.
Carefully. I kid, I kid.
SMD rework on SMT ROHS stuff is a pain. Carefully applied heat is really the only way. It’s a pain, especially with extremely fine pitch components.
For recalcitrant thru-hole stuff, I like to remove as much of the old solder with solder-wick as I can and then reflow the joint using lead solder before switching back to solder wick or a solder sucker.
FYI the “frosted” appearance of the hard-to-flow solder in the video is a giveaway that it is really much higher in tin content than it claims. If I was inspecting a standard board and saw that I would fail it as a cold or contaminated joint, on the new low-lead/lead-free stuff, that’s standard appearance.
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I always wet the tip first. The little bit of melted solder speeds the flow of heat into the joint. Then feed the solder wire in. Using a dry tip increases the time, you run the risk of damaging components or melting wire insulation.
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63/37 is better than 60/40. Lower melting point and it goes from melted to solid without going through the intermediate “plastic” state, like 60/40 does.
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If yours is like mine you can use genuine Hakko tips on it. Makes a difference!
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Yes. Lead free solder sucks. It doesn’t flow as well, requires much higher temperatures to melt, and you have the wonderful phenomenon of tin whiskers to deal with.
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I don’t mind lead-free. Soldering is one of those areas where I’m willing to spend a little more to avoid massive frustration and future problems. My choice is a Hakko iron, several different tips, Kester silver-bearing lead-free solder, and a flux pen. I can happily lay down hundreds of joints with those. (Yeah, I actually like soldering.)
Oh - and a fume extractor.
